The rich diversity of wildlife in southern Mexico
and Central America is in peril. Local governments are using
satellites to get a grip on a vast "corridor" system
of protected lands.

In an area of rich biodiversity,
where 7% of our planet's terrestrial species are packed onto
less than 1% of the planet's land, a rapidly growing human population
is struggling with widespread poverty that affects more than
20 million people. Many of these people survive through unsustainable
"slash and burn" agriculture, putting themselves and
the rain forest on a collision course with catastrophe.

Simultaneously promoting the local
economy while protecting forests and wildlife is the ambitious
goal of an international project called the Mesoamerican Biological
Corridor (CBM is the acronym for the name in Spanish).

The largest "sustainable development"
effort of its kind in the world, the CBM is a sprawling
web of protected and semi-protected lands that stretch the
entire length of Central America from southern Mexico to the
border of South America--a region known as "Mesoamerica."
The lands of the CBM are collectively managed by the governments
of the seven Central American countries and Mexico. Together,
these governments preserve some areas of the CBM and in others
promote limited, "sustainable" economic use of the
land.

"The human dimension is now
one of the most important factors for not only conservation but
also sustainable economic development," says Daniel Irwin,
a research scientist who has worked and lived in Central America
much of his life, and who now works at NASA's Marshall Space
Flight Center.

"It's
not just a matter of fencing off animals and keeping it separate,
because there are so many people who live in the region,"
Irwin says.

Sustainable development is a relatively
new direction in environmental thinking. It acknowledges that
people need to use nature's resources to survive, but it also
asserts that people must do so in an ecologically sensitive way,
or else those resources may not be there for future generations.

For example, farmers might be encouraged
to enrich the nitrogen in their existing fields by planting legumes
such as alfalfa, rather than cutting and burning more forest
when the soil becomes depleted. Another popular approach is to
use tax incentives to motivate a land owner to set aside some
of the forest on their property rather than developing it.

To maximize the ecological benefit
of saving these forests, the CBM maintains strips of land connecting
the forested areas--another relatively new idea in wildlife conservation
called "corridors."

Animals and plant seeds can then
move between the areas, reducing the threat of inbreeding or
local disasters wiping out a species. And they provide more space
for top carnivores such as jaguars who range long distances to
survive. That's why the network of connected areas as a whole
has more ecological value than the sum of its parts.

Below:
People and wildlife often
live in close proximity in Central America, and their needs sometimes
conflict. Photo courtesy CBM.

"Because you don't have
intense migrations like in the African savannah, your corridor
can serve its purposes and still allow certain kinds of human
uses," explains Archie Carr III, a veteran conservationist
who leads the Wildlife Conservation Society's projects in the
Caribbean. Carr led a project between 1990-95 called the Paseo
Pantera (Spanish for "path of the panther") that originally
established the corridor system that later became the CBM.

Coffee, for example, had traditionally
been grown under the shade of trees. This kind of coffee field
mimics the structure of a natural forest and thus provides good
habitat for wildlife.

"Some of this shade-grown coffee
would provide corridor functions probably perfectly well for
an enormous number of tropical creatures," Carr says.

But in modern times, a more productive,
sun-tolerant strain of coffee was introduced to the region, leading
to treeless coffee fields with little habitat for wildlife. Various
organizations including the CBM and the Rainforest Alliance are
now trying to persuade coffee farmers to return to the more ecological,
shade-grown system.

Watching from above

It's not easy for the region's environmental
managers to keep an eye on such a large area of land, though.
That's why the intergovernmental agency in charge of the corridor,
called the Central American Commission for Environment and Development
(CCAD), has recruited the bird's-eye view of NASA satellites
to help out.

"The
landscape-wide perspective that satellites provide is essential
for doing a large-scale conservation project like this,"
Irwin says.

"The rain forest is so thick
in many places that you can hardly see 10 feet in front of your
face," Irwin says. "Trying to survey such large areas
on foot is nearly impossible."

Right:
Teaching local decision
makers to understand and use satellite data is a part of the
agreement between NASA and CCAD. Pictured standing at bottom-left
is Daniel Irwin. Image courtesy NASA/CCAD.

To get the job done, Irwin and his
colleagues use data from an assortment of satellites. For assessments
on the scale of entire countries, they use data from the Moderate-resolution
Imaging Spectrometer (MODIS) on NASA's Terra and Aqua satellites.
This sensor takes images whose pixels each cover 250 meters of
ground, suitable for looking at such large scales. Landsat, on
the other hand, has a resolution of 30 meters, and is more useful
for closer looks.

NASA signed an agreement with CCAD in 1998 to use its
Earth-watching satellites--called the Earth Observing System--to
help the corridor project. One outcome of this collaboration
was a study using Landsat data from the 1990s that showed that
the corridor was indeed protecting the forests. About 80% of
forests inside the CBM still remained, compared with only about
31% outside the corridor. And annual forest clearing rates were
5.5 times higher outside the corridor than inside (1.44% versus
0.26%).

With help from the World Bank, the
team also assembled an ecosystem
map for all of Mesoamerica. The first of its kind to cover
the entire region, this map shows in detail where the rain forests,
lowlands, and croplands all lie--an invaluable tool for those
managing the CBM.

These managers use the satellite
data in other ways as well. For example, data from MODIS shows
the location of burning fires in the entire region in near real-time
(as in the image at the top of this article).

So far, however, the principal use
of the satellite data has been as a political tool, according
to Jorge Cabrera, the CCAD official in Central America handling
the collaboration with NASA.

"In
the case of the fires in the PetĂŠn and Yucatan regions
this year, givingthis information to the media succeeded
in mobilizing more political, institutional, and public interest
in the magnitude of the disaster," Cabrera said in an e-mail
interview (translated from Spanish).

Right:
Slash-and-burn agriculture
destroys forests and wildlife. This photo was taken in PetĂŠn,
Guatemala, by Daniel Irwin.

Planning for the future

In December, NASA signed a new agreement
with the CCAD and the World Bank to continue the use of satellites
for the corridor project, and to look into an innovative new
way of making the satellite data available.

The concept they're considering
is a live "dashboard" showing the state of the environment
in Central America as seen by NASA satellites in near real-time,
just as the dials on a car dashboard show the state of the car.
A computing "pipeline" would be designed that would
automatically gather the latest data from the satellites, process
the raw data into a relevant and useful form, and present this
user-friendly information to the people who need it: Central
American politicians, civic leaders, and even local students.

"The information would be available
in a timely manner for the Central American decision makers--the
ministers, the people who are really making the calls about the
environment down there," Irwin says.